Auto-detect *.sbt and "#!/usr/bin/env scala"

Auto-detect *.sbt (Scala Build Tool) files and files whose first line is
"#!/usr/bin/env scala" as Scala.
Fix syntax highlighting in help files.

Commit 844ce86 accidentally disabled Scala syntax highlighting
in help files if you are using a version of Vim that was
compiled without the "conceal" feature.

This patch preserves the part of 844ce86 that avoids an error
message, but also allows syntax highlighting to work.
Improve syntax-coloring speed

Syntax coloring was previously done by always starting all the way
at the beginning of the file.  This could cause Vim to become very
slow when editing .scala files.

With this patch, Vim will only look 100 lines back to get context
for syntax-coloring.
oops, minline appeared twice in syntax file
Merge pull request #12 from mmorearty/patch-2

Auto-detect *.sbt and "#!/usr/bin/env scala"
Merge pull request #16 from mmorearty/patch-3

Fix syntax highlighting in help files.
Merge pull request #17 from mmorearty/patch-4

Improve syntax-coloring speed
make and tagbar support in scala.
Merge pull request #19 from pankajroark/master

make and tagbar support
Merge branch 'master' of https://github.com/derekwyatt/vim-scala

Conflicts:
	after/syntax/help.vim
	ftplugin/scala.vim